Effects of a 12-month prophylactic programme on selected oral bacterial populations on root surfaces with active and inactive carious lesions.

In 15 caries-active patients, with a total of 770 exposed root surfaces, the effect of fluoride therapy and professional tooth cleaning was studied during a 1-year period. Dental plaque from 92 of the root surfaces and whole saliva samples were analysed at baseline and after 12 months for the presence of specific bacteria. The results showed that the number of active carious lesions had decreased from 99 to 46, while the inactive lesions had increased from 69 to 124. Of the active lesions which had been converted into inactive lesions, most were on the buccal and fewest were located on the distal surfaces. Lower plaque scores were found on sound and inactive root surfaces compared to active surfaces. The salivary concentrations of mutans streptococci and lactobacilli remained constant during the 12-month observation period. There was a tendency for higher levels of Streptococcus mutans in plaque from active lesions compared with sound root surfaces, whereas an inverse relationship was noted for the Streptococcus oralis group. No significant differences in the Actinomyces naeslundii counts were detected. In conclusion, the 12-month prophylactic programme had an effect on the clinical surface characteristics of root caries, but the components of the oral microflora selected for study seemed to be relatively unaffected during the observation period.